STRUCTURE AND COMPOSITION OF COKE DEPOSITED ON COMPONENTS OF FCC CATALYST DURING GAS OIL CRACKING

An analytical method combining silica gel column chromatography separation, GC/MS and FDMS was developed to determine the composition and structure of the soluble coke((S-coke)). The characteristics of coke deposited on Y zeolites and the matrix of FCC catalyst during gas oil cracking under different reaction temperatures were investigated. The results indicated that, under lower reaction temperatures (400-460℃), most of the coke deposited on Y zeolites were soluble. Though the coke content was lower on USY zeolites, the coke substance was more condensed than those on REY zeolites. Under a higher temperature 520℃, insoluble coke(Ins-coke) appeared to be the main component of the coke. Only a little part of coke on the matrix was soluble even under a lower reaction temperature 400℃, which indicated that coke substance deposited on the matrix was more condensed than on Y zeolites. The (S-coke) comprised mainly methyl polyaromatic derivatives with 3-8 aromatic rings, having methyl amounts ≤8. The Ins-coke was amorphous, with aromatic H/C ratio: 0.3-0.5.